Portable battery



FIG. 1 is a front perspective view of a portable battery showing my new design.

FIG. 2 is a front view thereof.

FIG. 3 is a rear view thereof.

FIG. 4 is the left side view thereof.

FIG. 5 is a right side view thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the drawings represent portions of the article that form no part of the claimed design. 

CLAIM The ornamental design for a portable battery, as shown and described. 